The candidate's overall career goal is to be an independent researcher who contributes to the development and application of radiological technology as well as the assessment of the role of such techniques in the health care system. This Research Career Award has three broad objectives that will enable her progression to an independent researcher. First, it will expand her research skills through a program of formal coursework and informal mentoring focused on advanced techniques in data analysis, particularly decision analysis, cost-effectiveness analysis, and epidemiological methods for clinical prediction rules. Second, the candidate will gain practical experience through the development and implementation of a randomized controlled study assessing the impact of sinus CT on the use of antibiotics for patients with acute sinusitis, and to develop and validate clinical prediction rules through the randomized clinical trials. Third, she will establish a research network of local institutions to enable future investigations of the role of diagnostic technologies in infectious disease in the head and neck. The research portion of this Research Career Award proposes to develop practical strategies for limiting inappropriate antibiotic use to those patients most likely to benefit. Sinusitis is a highly prevalent disease and the fifth most common diagnosis for which an antibiotic is prescribed. The unnecessary use of antibiotics leads not only to an increase in health care expenditure but also to the spread of antibiotic-resistant organisms. The specific aims of this proposal are: 1) to determine if initial diagnostic work-up with CT decreases antibiotic use for patients presenting with acute sinusitis symptoms; 2) to determine whether the inclusion of CT in an initial diagnostic work-up affects patient outcomes; and 3) to determine whether sinus CT decreases overall healthcare costs and increases cost-effectiveness for patients with acute sinusitis. She will perform a randomized controlled trial of patients with acute sinusitis symptoms whose physicians plan antibiotic treatment. These patients will be allocated to receive either sinus CT or no CT at the time of initial diagnosis, with follow-up at 1, 2, and 8 weeks and 6 months. For both groups of patients, the candidate will ascertain antibiotic use (Aim 1), clinical outcome (Aim 2), as well as societal costs (Aim 3).